The present invention relates to a bulb-form lamp and its manufacturing method.
A conventional bulb-form lamp, for example, a compact self-ballasted fluorescent lamp accommodates a light generating tube 4 and a lighting circuit 5 for lighting the light generating tube 4, in an envelope 29 including a globe 1 and a casing 28, as shown in FIG. 12.
In one end of the casing 28, a cap 30 is inserted and caulked to be fixed. The cap 30 has a screw-shaped shell 31 screw and an eyelet 33 provided at one end of the shell 31 via a glass insulting part 32. The shell 31, the insulting part 32 and the eyelet 33 are integrally formed by embedding each part of the shell 31 and the eyelet 33 in the insulating part 32.
Japanese Patent Laid-Open No. 9-97589 specification discloses another compact self-ballasted fluorescent lamp including a holder member (a casing) provided with a screw cap on an outer periphery of a cylindrical part formed at its one end. The screw cap is provided with a longitudinally formed recess, in which a feeding terminal forming a strip-shaped side terminal is provided.
However, such a conventional bulb-form lamp, for example, the compact self-ballasted fluorescent lamp shown in FIG. 12, has a problem that the casing 28 and the cap 30 are separately manufactured and then assembled together, resulting in many steps in process and low productivity efficiency.
In addition, a socket of a lighting equipment wherein the conventional compact self-ballasted fluorescent lamp is fitted, has been increasingly provided with a strip-shaped lamp holder for contact with the shell 31 or the feeding terminal.
In case where the compact self-ballasted fluorescent lamp disclosed in Japanese Patent Laid-Open No. 9-97589 specification is fitted in such a socket with the strip-shaped lamp holder, there is a problem that the strip-shaped lamp holder and the strip-shaped feeding terminal readily catch against each other, failing in fitting of the lamp in the socket. Another problem is that the lamp holder and the feeding terminal do not attain right positioning for contact therebetween, failing in lighting.
The present invention is achieved for solving such problems to provide a bulb-form lamp, including a few components and manufactured at low cost, which can be easily fitted in a socket of a lighting equipment and ensure electrical contact between the shell and the socket of the lighting equipment.
The present invention also provides a bulb-form lamp manufacturing method which enables reduction in the number of steps and improvement in productivity.
A bulb-form lamp according to the present invention has a configuration including a shell surrounding one end of a casing, the shell being molded integrally with one end of the casing to make contact with an outer surface of the casing leaving substantially no gap.
By such a configuration as including a few components and being able to be manufactured at a low cost, for example, when the shell is fitted in a socket of a lighting equipment having a strip-shaped lamp holder, the shell does not catch against the lamp holder so that it can be easily fitted in the socket and that the shell can make electrical contact with the lamp holder wherever the lamp holder is.
A bulb-form lamp manufacturing method according to the present invention uses a method for molding the shell integrally with one end of the casing leaving substantially no gap at the same time as molding the casing by using a die assembly.
Such integral molding of the shell with the casing when the casing is being molded eliminates the need for each conventional manufacturing step of the casing and the cap, and a step for assembling thereof, resulting in reduction in the number of steps.